/*
 * This ESP32 code is created by esp32io.com
 *
 * This ESP32 code is released in the public domain
 *
 * For more detail (instruction and wiring diagram), visit https://esp32io.com/tutorials/esp32-gas-sensor
 */

#define DO_PIN 16  // ESP32's pin GPIO16 connected to DO pin of the MQ2 sensor

void setup() {
  // initialize serial communication
  Serial.begin(9600);
  // initialize the ESP32's pin as an input
  pinMode(DO_PIN, INPUT);

  Serial.println("Warming up the MQ2 sensor");
  delay(20000);  // wait for the MQ2 to warm up
}

void loop() {
  int gasState = digitalRead(DO_PIN);

  if (gasState == HIGH)
    Serial.println("The gas is NOT present");
  else
    Serial.println("The gas is present");
}